Determine the role of the brush border in the transport mechanisms of the proximal nephron for sodium phosphate, glucose, amino acids and other metabolites. Thereby, we expect to define the functional consequences of the striking loss of these organelles in the ischemic kidney. Describe the processes of repair and reconstitution of the brush border after loss during ischemic injury. Biochemical, ultrastructural and autoradiographic methods will be used to define the cell biology of the repair process. Define the internal mechanisms which control renal vascular resistance at normal and reduced blood pressure. The isolated perfused kidney will be used to evaluate the interplay of renal hormones in control of the renal circulation. Evaluate the mechanism and significance of decreased renal blood flow in experimental acute renal failure. Study the mechanisms of action of mannitol in renal ischemia and acute renal failure.